This invention relates generally to earth boring, especially to improvements to bits having lubrications systems that use pressure compensators to minimize the differential pressure across the seals between the rotatable cutters and their supporting, cantilevered bearing pins or shafts.
2. Description of the Prior Art
The commercially viable earth boring or rock bit has a lubrication system that includes a pressure compensator to balance the pressure of the drilling fluid with that of the lubricant inside bit. Advantageously, this minimizes the pressure differential across the bearing seal that separates the drilling fluid from the lubricant in each leg of the conventional three cone rock bit.
Each of the three legs that form the body of the current, commercially successful rock bit contains a complex network of holes and passages to support the compensator and lubrication system. The resulting complexity of manufacture and assembly adversely affects the reliability and performance of an unacceptable number of rock bits. Previously, rock bit patents include those that have compensator systems in each bearing shaft or pin. None have withstood the test of time--at least not in the commercial sense. Thus, the quest for improvement continues.